Twenty-three thousand pregnant women and their children registered in the Collaborative Perinatal Research Project from onset of the study thru March, 1963 were studied prospectively, clinically, and serologically for Toxoplasmosis. Major maternal findings included: constant exposure to Toxoplasmosis thruout child-bearing years; higher exposures among Negroes and women born in Puerto Rico, and no correlation with urban vs. rural life. Pediatric findings in the 47 high risk pregnancies within this group included: 2 cases of clear congenital Toxoplasmosis and 10 suspect; a higher rate of undefined abnormalities in the high risk group, and a higher rate of low IQs in the case group compared to controls. The latter were Collaborative Perinatal Research Project gravidae with negative serologies and matched for age, race, LMP, participating medical centers. These and other preliminary findings were presented at the Seminar on Toxoplasmosis held in conjunction with the Thirteenth Annual Congress, of the Medical International Women's Association in Paris, France, September, 1972. Preparation of manuscript for publication was delayed pending completion of collection and processing of the CPRP data. The findings will now be submitted to publishers.